Together with the Pisan-style Romanic church of San Simplicio, Pedres castle – also known as Pedes castle or Pedreso castle – symbolises and embodies the culmination of the Judicate of Olbia. The fortress characterises the whole southern area of the valley where Olbia is situated, which is entirely dominated by this building, even though the cliff it stands on is only 89 metres high. Built of local stone in the middle of the 1200s during the Visconti’s domination of the Judicate of Gallura, the castle was later used by the Pisans to defend against the attack perpetrated by the Aragonese forces.